The down-bound lane of James Mountain Road will be closed Monday night.
Crews will make emergency repairs to a water main break at the base of the hill near St. Joseph's Hospital. Motorists should use Claremont Access or Jolley Cut to get down the mountain.
The lane will be closed from 10 p.m. Monday until 7 a.m. Tuesday.
Hamilton police will be stationed at the top of the access so emergency vehicles can make it to the hospital.
Some properties in the area may also have a temporary change in water pressure.